Subjects: Geosciences >> Space Physics Subjects: Geosciences >> Marine Sciences submitted time 2017-03-10
Abstract：在建立雷达高度计海况偏差(Sea State Bias, SSB)非参数模型时，通常会用到局部线性回归(Local Linear Regression, LLR)估计器，而传统的局部线性回归估计器涉及高维矩阵运算，当建模的数据量较大时，估计海况偏差需要大量的时间，从而使得非参数估计方法很难用于高维海况偏差模型。该文提出一种改进的局部线性回归(Improved Local Linear Regression, ILLR)估计器，可以避免传统的LLR估计器所需的高维矩阵运算，在不影响海况偏差估计结果的条件下，将局部线性回归估计器获取加权函数的时间复杂度由降低为，从而大幅地降低估计海况偏差所需的时间，为实现高维非参数海况偏差模型的实时运算奠定了基础。
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Awaiting Review
Subjects: Geosciences >> Space Physics Subjects: Geosciences >> Marine Sciences submitted time 2017-03-10
Abstract：海况偏差(Sea State Bias,SSB)是雷达高度计测量海面高度的重要误差源。目前,业务化运行的雷达高度计的海况偏差校正都是采用基于风速(U)和有效波高(SWH)的2维经验模型方法,其海况偏差校正不确定度约为2cm。该文提出一种基于交叉点数据和3维非参数模型的海况偏差估计方法,该方法利用星下交叉点数据,采用基于U,SWH以及平均波周期(MWP)的3维非参数模型进行海况偏差估计。该文利用这种估计方法对Jason-2卫星雷达高度计2009~2011年3年的数据进行了处理,将处理结果与Jason-2卫星高度计的地球物理数据集(Geophysical Data Records,GDR)中的海况偏差校正项进行对比,结果表明该文提出的海况偏差估计方法平均能降低1.64 cm2的交叉点海面高度不符值的方差和0.92 cm2的沿轨海面高度异常值的方差,分别对应于1.28 cm和0.96 cm的均方根(RMS)海面高度,这对于提高高度计数据产品的精度具有重要意义。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： In absolute altimeter calibration campaigns,the Sea Surface Height(SSH)series derived from the in-situ Differential GPS(DGPS)buoys always include high frequency errors such as wind waves and instrumental noises. The former can be removed by low pass filters,while the latter can not,because the noises are white and can spread in the whole frequency band of interest.In this paper,the Singular Spectrum Analysis(SSA)method was applied to solve the problem,and select criteria of the embedding dimension and intercepting length.Simulations based on this innovative method were executed,the effectiveness in removing the instrumental noise and the selction criteria was validated.Finally,SSH series derived from an in-situ DGPS buoy experiment were processed by this method,and the study suggested that the processed series were smoother compared to the original series,and had some improvements in accuracy.Therefore,the validity of the SSA method was demonstrated.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-05-03
Abstract： The Range Migration Correction (RMC) is a key technique of synthetic aperture radar altimeter which is more precise than the conventional radar altimeter. Because of the satellite motion, the distance change between the satellite and the observed target will bring about some residual errors, but they are ignored in the existing RMC algorithms. In this paper, the influences of the vertical and horizontal velocities of the satellite are studied, then an RMC model is builded, and finally a new RMC algorithm which corrects not only the slant range error but also the residual errors is proposed. The simulation results show that this new algorithm can obtain more accurate outcomes. �2015, Science Press. All right reserved.
Peer Review Status:Awaiting Review
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